Photothermal Reliability Testing of a Multilayer Coating—Substrate Assembly: A Theoretical Approach

1998 ◽  
Vol 120 (1) ◽  
pp. 82-88 ◽  
Author(s):  
T. Elperin ◽  
G. Rudin
Keyword(s):  
Laser Beam ◽  
Probe Beam ◽  
Thermal Stresses ◽  
Deflection Angle ◽  
Multilayer Coating ◽  
Pump Laser ◽  
Reliability Testing ◽  
Fourier Number ◽  
The Deflection Angle ◽  
Pump Laser Beam

The paper presents the theoretical principles underlying the method for photothermal reliability testing of a multilayer coating-substrate assembly. In this method, the assembly is irradiated by the pump laser beam which causes heating and formation of thermal stresses in an assembly. The irradiated surface is monitored by a weak probe beam of another laser to detect the buckling of the coating. The two-dimensional distributions of temperature and thermal stresses in an assembly heated by the pump laser beam are obtained from the solution of the thermal elasticity problem. The developed mathematical procedure is based on the expansion of the Laplace and Hankel transforms of temperature and displacement distributions in series of a small parameter, which is of the order of the ratio of a coating thickness to a pump beam radius. The explicit expressions for the stress tensor components in the layers of a coating and the probe beam deflection angle are derived. Calculations show that the dependence of the deflection angle on a Fourier number is nonmonotone and attains a maximum at some value of the Fourier number. The latter property of the dependence of the deflection angle on the Fourier number can be used for detecting subsurface structural defects in an assembly.

Strong terahertz radiation from air plasmas generated by an aperture-limited Gaussian pump laser beam

2009 ◽  
Vol 94 (10) ◽  
pp. 101502 ◽  
Author(s):  
Xiao-Yu Peng ◽  
Chun Li ◽  
Min Chen ◽  
Toma Toncian ◽  
Ralph Jung ◽  
...  
Keyword(s):  
Laser Beam ◽  
Terahertz Radiation ◽  
Pump Laser ◽  
Air Plasmas ◽  
Pump Laser Beam

Studies of Multichannel Photothermal Refraction for the Measurement of Absolute Absorptivity

1992 ◽  
Vol 46 (10) ◽  
pp. 1583-1586
Author(s):  
Leon N. Klatt
Keyword(s):  
Heat Transfer ◽  
Refractive Index ◽  
Laser Beam ◽  
Theoretical Description ◽  
Pump Laser ◽  
Transfer Model ◽  
Nonlinear Relationship ◽  
Experimental Conditions ◽  
Photochemical Processes ◽  
Pump Laser Beam

Multichannel crossed-beam photothermal refraction experiments have been performed. Iron(II)-phenanthroline in methanol was the test solute. The response as a function of concentration exhibited a nonlinear relationship, which does not agree with the current theoretical description of the phenomena. Although photophysical and photochemical processes were not totally eliminated as possible causes of the nonlinear concentration response, arguments are presented which indicate, for the experimental conditions employed in this study, that these processes are negligible. It is proposed that the heat transfer model must be modified to include refractive index gradients in both the radial and axial coordinates of the pump laser beam.

Transverse scattering of radiation upon focusing of pump laser beam to line in experiments on X-ray laser

2011 ◽  
Vol 111 (2) ◽  
pp. 184-190 ◽  
Author(s):  
L. M. Lavrov ◽  
A. V. Bessarab ◽  
D. I. Martsovenko ◽  
F. A. Starikov ◽  
A. A. Andreev ◽  
...  
Keyword(s):  
Laser Beam ◽  
Pump Laser ◽  
X Ray ◽  
Pump Laser Beam ◽  
Transverse Scattering

scholarly journals Tuning and focusing THz pulses by shaping the pump laser beam profile in a nonlinear crystal

2009 ◽  
Vol 17 (2) ◽  
pp. 592 ◽  
Author(s):  
Ciro D'Amico ◽  
Marc Tondusson ◽  
Jérome Degert ◽  
Eric Freysz
Keyword(s):  
Laser Beam ◽  
Nonlinear Crystal ◽  
Beam Profile ◽  
Pump Laser ◽  
Laser Beam Profile ◽  
Pump Laser Beam

Frequency measurement using Rayleigh scattering from a BEC

2015 ◽  
Vol 29 (08) ◽  
pp. 1550051
Author(s):  
A. B. Bhattacherjee ◽  
S. De
Keyword(s):  
Laser Beam ◽  
Time Evolution ◽  
Rayleigh Scattering ◽  
State Of The Art ◽  
Frequency Measurement ◽  
Bose Gas ◽  
Pump Laser ◽  
Initial Momentum ◽  
Momentum State ◽  
Pump Laser Beam

We propose to use superradiant Rayleigh scattering from degenerate Bose gas to detect unknown frequencies coupled to the pump laser beam. Theoretically we show a measurement of the time evolution of population at the initial momentum state could determine the unknown frequency with respect to a known one at which the pump laser's frequency modulates. We show a range of frequencies from kHz to MHz could be determined with this method at the currently available state-of-the-art technology.

scholarly journals Generation of plasma wave and third harmonic generation at ultra relativistic laser power

2007 ◽  
Vol 25 (2) ◽  
pp. 211-218 ◽  
Author(s):  
M. K. Gupta ◽  
R. P. Sharma ◽  
S. T. Mahmoud
Keyword(s):  
Laser Beam ◽  
Plasma Wave ◽  
Harmonic Generation ◽  
Laser Power ◽  
Third Harmonic Generation ◽  
Pump Laser ◽  
Third Harmonic ◽  
The Third ◽  
Paraxial Ray ◽  
Pump Laser Beam

This paper investigates the generation of plasma wave and third harmonic generation in hot collision less plasma by a Gaussian ultra intense laser beam, when relativistic and ponderomotive nonlinearities are operative. First, we derive the dynamical equation for the pump laser beam when these two nonlinearities are operative. The solution of pump laser beam has been obtained within the paraxial ray approximation. Filamentary structures of the laser beam are observed. On account of V→ × B→ force, the generation of plasma wave at second harmonic frequency has been studied in these filamentary structures. Interaction of the plasma wave with the incident laser beam generates the third harmonic. For the typical laser plasma parameters: Nd: YAG laser beam (λ = 1064 nm), ro = 15 µm, laser power flux equals 6 × 1017 W/cm2, electron density equals no = 1.9 × 1019 per cm3, the third harmonic yield comes out to be equals to 2 × 10−6.

scholarly journals Polarization Measurement of Cs Using the Pump Laser Beam

2017 ◽  
Vol 9 (6) ◽  
pp. 1-8 ◽  
Author(s):  
Rujie Li ◽  
Wei Quan ◽  
Jiancheng Fang
Keyword(s):  
Laser Beam ◽  
Polarization Measurement ◽  
Pump Laser ◽  
Pump Laser Beam

scholarly journals Quantitative evaluation indexes of the spatial steering effect of directional perforation hydraulic fractures

2021 ◽  
pp. 014459872110102
Author(s):  
Lu Weiyong ◽  
He Changchun
Keyword(s):  
Quantitative Evaluation ◽  
Hydraulic Fracture ◽  
Deflection Angle ◽  
Hydraulic Fractures ◽  
Principal Stress Direction ◽  
Perforation Hole ◽  
Evaluation Indexes ◽  
Initiation Pressure ◽  
The Deflection Angle ◽  
Bending Fracture

To better evaluate the spatial steering effect of directional perforation hydraulic fractures, evaluation indexes for the spatial steering effect are first proposed in this paper. Then, these indexes are used to quantitatively evaluate existing physical experimental results. Finally, with the help of RFPA2D-Flow software, the influence of perforation length and azimuth on the spatial steering process of hydraulic fracture are quantitatively analysed using four evaluation indexes. It is shown by the results that the spatial deflection trajectory, deflection distance, deflection angle and initiation pressure of hydraulic fractures can be used as quantitative evaluation indexes for the spatial steering effect of hydraulic fractures. The deflection paths of directional perforation hydraulic fractures are basically the same. They all gradually deflect to the maximum horizontal principal stress direction from the perforation hole and finally represent a double-wing bending fracture. The deflection distance, deflection angle and initiation pressure of hydraulic fractures increase gradually with increasing perforation azimuth, and the sensitivity of the deflection angle to the perforation azimuth of hydraulic fractures also increases. With increasing perforation length, the deflection distance of hydraulic fractures increases gradually. However, the deflection angle and initiation pressure decrease gradually, as does the sensitivity.

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